2. Large transformers, when used for some time, become very hot and are cooled by circulating oil. The heating of the transformer is due to -
1. the heating effect of current alone
2. hysteresis loss alone
3. both the heating effect of current and hysteresis loss
4. intense sunlight at noon

10. Suitable impurities are added to a semiconductor depending on its use. This is done in order to?
1. Increase its life
2. Enable it to withstand higher voltages
3. Increase its electrical conductivity
4. Increase its electrical resistivity
Chemistry
1. The nucleus of an atom consists of
1. electrons and neutrons
2. electrons and protons
3. protons and neutrons
4. All of the above